Isolation of a complementary DNA fragment of hepatitis C virus in Taiwan revealed significant sequence variations compared with other isolates.

To clone and characterize hepatitis C virus strains present in Taiwan, RNA was extracted from liver tissue collected from a patient during the acute phase of posttransfusion non-A, non-B hepatitis. RNA was then subjected to complementary DNA synthesis and the polymerase chain reaction, using primers derived from the original nucleotide sequence of the United States hepatitis C virus strain. A complementary DNA clone, HCV-T3, containing 552 base pairs of hepatitis C virus complementary DNA sequences was isolated and characterized. The homologies in nucleotide sequence between the Taiwan isolate and either the United States or Japan isolate were 80.1% and 91.5%, respectively. However, most of the nucleotide changes occurred in the third base positions, resulting in much higher homologies in amino acid sequence of 91.8% and 97.3%, respectively. Amplification of the less conserved region of hepatitis C virus genome with the polymerase chain reaction was improved by use of primers with nucleotides matched to the local strain. Finally, in addition to the liver and serum, the viral genome was also demonstrated in the spleen tissue by similar methods, suggesting another possible target for hepatitis C viral infection. These findings indicate that there is considerable heterogeneity in hepatitis C virus genomes isolated from different areas of the world.